# This module contains several routines that help recognizing sound# files.## Function whathdr() recognizes various types of sound file headers.# It understands almost all headers that SOX can decode.## The return tuple contains the following items, in this order:# - file type (as SOX understands it)# - sampling rate (0 if unknown or hard to decode)# - number of channels (0 if unknown or hard to decode)# - number of frames in the file (-1 if unknown or hard to decode)# - number of bits/sample, or 'U' for U-LAW, or 'A' for A-LAW## If the file doesn't have a recognizable type, it returns None.# If the file can't be opened, IOError is raised.## To compute the total time, divide the number of frames by the# sampling rate (a frame contains a sample for each channel).## Function whatraw() calls the "whatsound" program and interprets its# output. You'll have to guess the sampling rate by listening though!## Function what() calls whathdr() and if it doesn't recognize the file# then calls whatraw().## Finally, the function test() is a simple main program that calls# what() for all files mentioned on the argument list. For directory# arguments it calls what() for all files in that directory. Default# argument is "." (testing all files in the current directory). The# option -r tells it to recurse down directories found inside# explicitly given directories.## The file structure is top-down except that the test program and its# subroutine come last.#------------------------------------------------------## Guess the type of any sound file, raw or with header ##------------------------------------------------------#defwhat(filename):res=whathdr(filename)ifnotres:res=whatraw(filename)returnres#-----------------------------## Guess the type of raw sound ##-----------------------------#defwhatraw(filename):# Assume it's always 1 channel, byte-sized samples# Don't assume anything about the rateimportosfromstatimportST_SIZE# XXX "whatsound" should be part of the distribution somehow...cmd='whatsound '+filename+' 2>/dev/null'cmd='PATH=$PATH:/ufs/guido/bin/sgi\n'+cmdpipe=os.popen(cmd,'r')data=pipe.read()sts=pipe.close()ifsts:returnNoneifdata[:13]=='-t raw -b -s ':type='sb'sample_size=8elifdata[:13]=='-t raw -b -u ':type='ub'sample_size=8elifdata[:13]=='-t raw -b -U ':type='ul'sample_size='U'else:returnNonetry:frame_count=os.stat(filename)[ST_SIZE]exceptIOError:frame_count=-1returntype,0,1,frame_count,sample_size#-------------------------## Recognize sound headers ##-------------------------#defwhathdr(filename):f=open(filename,'r')h=f.read(512)fortfintests:res=tf(h,f)ifres:returnresreturnNone#-----------------------------------## Subroutines per sound header type ##-----------------------------------#tests=[]deftest_aifc(h,f):importaifcifh[:4]<>'FORM':returnNoneifh[8:12]=='AIFC':fmt='aifc'elifh[8:12]=='AIFF':fmt='aiff'else:returnNonef.seek(0)try:a=aifc.openfp(f,'r')except(EOFError,aifc.Error):returnNonereturn(fmt,a.getframerate(),a.getnchannels(), \
a.getnframes(),8*a.getsampwidth())tests.append(test_aifc)deftest_au(h,f):ifh[:4]=='.snd':f=get_long_beelifh[:4]in('\0ds.','dns.'):f=get_long_leelse:returnNonetype='au'hdr_size=f(h[4:8])data_size=f(h[8:12])encoding=f(h[12:16])rate=f(h[16:20])nchannels=f(h[20:24])sample_size=1# defaultifencoding==1:sample_bits='U'elifencoding==2:sample_bits=8elifencoding==3:sample_bits=16sample_size=2else:sample_bits='?'frame_size=sample_size*nchannelsreturntype,rate,nchannels,data_size/frame_size,sample_bitstests.append(test_au)deftest_hcom(h,f):ifh[65:69]<>'FSSD'orh[128:132]<>'HCOM':returnNonedivisor=get_long_be(h[128+16:128+20])return'hcom',22050/divisor,1,-1,8tests.append(test_hcom)deftest_voc(h,f):ifh[:20]<>'Creative Voice File\032':returnNonesbseek=get_short_le(h[20:22])rate=0if0<=sbseek<500andh[sbseek]=='\1':ratecode=ord(h[sbseek+4])rate=int(1000000.0/(256-ratecode))return'voc',rate,1,-1,8tests.append(test_voc)deftest_wav(h,f):# 'RIFF' <len> 'WAVE' 'fmt ' <len>ifh[:4]<>'RIFF'orh[8:12]<>'WAVE'orh[12:16]<>'fmt ':returnNonestyle=get_short_le(h[20:22])nchannels=get_short_le(h[22:24])rate=get_long_le(h[24:28])sample_bits=get_short_le(h[34:36])return'wav',rate,nchannels,-1,sample_bitstests.append(test_wav)deftest_8svx(h,f):ifh[:4]<>'FORM'orh[8:12]<>'8SVX':returnNone# Should decode it to get #channels -- assume always 1return'8svx',0,1,0,8tests.append(test_8svx)deftest_sndt(h,f):ifh[:5]=='SOUND':nsamples=get_long_le(h[8:12])rate=get_short_le(h[20:22])return'sndt',rate,1,nsamples,8tests.append(test_sndt)deftest_sndr(h,f):ifh[:2]=='\0\0':rate=get_short_le(h[2:4])if4000<=rate<=25000:return'sndr',rate,1,-1,8tests.append(test_sndr)#---------------------------------------------## Subroutines to extract numbers from strings ##---------------------------------------------#defget_long_be(s):return(ord(s[0])<<24)|(ord(s[1])<<16)|(ord(s[2])<<8)|ord(s[3])defget_long_le(s):return(ord(s[3])<<24)|(ord(s[2])<<16)|(ord(s[1])<<8)|ord(s[0])defget_short_be(s):return(ord(s[0])<<8)|ord(s[1])defget_short_le(s):return(ord(s[1])<<8)|ord(s[0])#--------------------## Small test program ##--------------------#deftest():importsysrecursive=0ifsys.argv[1:]andsys.argv[1]=='-r':delsys.argv[1:2]recursive=1try:ifsys.argv[1:]:testall(sys.argv[1:],recursive,1)else:testall(['.'],recursive,1)exceptKeyboardInterrupt:sys.stderr.write('\n[Interrupted]\n')sys.exit(1)deftestall(list,recursive,toplevel):importsysimportosforfilenameinlist:ifos.path.isdir(filename):printfilename+'/:',ifrecursiveortoplevel:print'recursing down:'importglobnames=glob.glob(os.path.join(filename,'*'))testall(names,recursive,0)else:print'*** directory (use -r) ***'else:printfilename+':',sys.stdout.flush()try:printwhat(filename)exceptIOError:print'*** not found ***'